Question

For complete combustion of methanol
$CH_3OH(I)+\frac 32O_2(g)→CO_2(g)+2H_2O(I)$
the amount of heat produced as measured by bomb calorimeter is $726$ kJ mol–1 at $27°C$. The enthalpy of combustion for the reaction is $x \ kJ mol^{–1}$, where $x$ is ______ . (Nearest integer)
(Given: $R= 8.3 \ JK^{–1}mol^{–1}$)

Answer 1

$CH_3OH(I)+\frac 32O_2(g)→CO_2(g)+2H_2O(I)$
The enthalpy of combustion for the reaction,
$ΔH=ΔU+Δn_gRT$
$ΔH=−726 kJ+(−\frac 12)×8.3×300$
$ΔH≃ –727\ kJmol^{–1}$

So, the answer is $727$.